can you change the output on a bosch internaly regulated alternator ?

[James Sweet]

The suppression myths are all a bunch of BS propagated by people who
sell snake oil. If a car company developed a way to significantly
increase fuel economy without greatly adding to the production cost,
they would be all over it like flies on poop and they wouldn't be
spending billions of dollars to develop expensive and difficult to
produce hybrids instead of cheap to build and highly profitable trucks
and SUVs.

There are laws of physics that dictate the maximum amount of energy that
can be extracted from the fuel by an internal combustion piston engine,
and current designs are approaching that limit.

 

[Tony]

Have you seen the kinetic energy transmissions (KERS) they're using in
Formula one?
80 extra horsepower for ~6 seconds.
Seems like black magic to me.

Yes, it is 'Kinetic Energy RECOVERY systems'. When a car uses its
brakes the kinetic energy is normally converted to heat. In F1 now when
they brake they convert some kinetic energy into electricity instead of
heat (in the brakes) and store it in a battery. Or in one team they
convert it into momentum of a spinning flywheel. An electric motor than
assist the engine during the 6s, yes they are hybrids!

There is no magic, its simple physics. You can do this in an internal
combustion car by disconnecting the battery for long periods and
charging during braking. As a result you brake less hard and convert
some energy to stored electricity, but I suspect the result wil be less
than impressive. I did see one performance device that disconnected the
battery during acceleration, not huge benefits but perfectly valid.
Increasing the alternator output may help with this, but I doubt a
simple regulator change would be enough and it requires another device
to control when to charge (ie during braking or if voltage too low).

 

[Tony]

The suppression myths are all a bunch of BS propagated by people who
sell snake oil. If a car company developed a way to significantly
increase fuel economy without greatly adding to the production cost,
they would be all over it like flies on poop and they wouldn't be
spending billions of dollars to develop expensive and difficult to
produce hybrids instead of cheap to build and highly profitable trucks
and SUVs.

There are laws of physics that dictate the maximum amount of energy that
can be extracted from the fuel by an internal combustion piston engine,
and current designs are approaching that limit.

I watched that suppression myth about GM killing the EV1, seemed very
believable to me, but yes you can never know who has a VI. I imagined
that fuel economy was the last thing they want to promote, but what goes
around comes around. My research over the last year or so has shown
that series hybrids can easily achieve 100mpg on fuel power alone. Once
cars like this are out and the mpg well known, who would buy a new I.C.
only car? All that engine development would be out the window as its
much easier to charge a battery efficiently at a fixed rev, using an
engine matched to average load (not peak), rather than drive a hugely
varying load (the wheels).

With current IC engines, they maybe getting more efficient but the
energy they create is still wasted alot. Heat goes out as mostly waste
, energy is used to drive various engine ancilaries (water pump, turbo,
steering) etc, and of course the old favourite ..tickover ,just keeping
it going.

 

[Tony]

The regulator in an automotive alternator does not regulate the output
voltage directly as a linear series pass regulator such as the
ubiquitous 3 terminal regulators used in many small electronic devices
does.

What it does do is control the field excitation current in response to
the output voltage of the alternator. As load increases and the voltage
starts to drop, the excitation current increases which increases the
output to compensate, the other effect being it increases the mechanical
load on the engine. The primary advantage of an alternator over an old
fashioned generator is that the brushes that transfer power to the
rotating assembly need only handle the current to the field coil in the
rotor rather than the entire output as is the case with a generator.

A standard automotive alternator can produce well over 100V if you drive
the excitation balls to the wall directly off the 12V battery with no
regulator. Indeed, it's a common trick used to run line voltage
incandescent lights and power tools driven by universal motors in
emergencies. Obviously one must first disconnect the output from the 12V
electrical system before doing this, and it likely does no favors for
the alternator but it does work.

In a nutshell, these adjustable regulators allow one to set the
reference voltage in the regulator against which the output is compared
to control the field current, which allows you to adjust the output. As
for reasons to do this, in many cars, the electrical system is not
really adequate. Older designs that got more and more accessories added
as they matured have more and more load on the system, and when you add
to that aftermarket devices you load things even further. Voltage drop
in the wiring and connectors that would be insignificant in a 120V or
240V household circuit become very significant when you only have ~12V
to work with, so sometimes boosting the stock alternator voltage up a
hair works nicely to compensate for losses elsewhere. Really it would be
better to rewire the entire car with heavier gauge wire and better
connectors throughout, but in most cases that's not really practical.

Thanks thats a helpful explanation. Still find it hard to understand
how if the problem is really deficient wiring, that bringing the voltage
up will reduce dimming when varying loads are applied, although I guess
it increases the low level. But I do see how that can help with
charging a battery in a caravan.

Really what you want is to isolate the battery/alternator/starter system
and regulate outside of it, preferably using a high efficiency switch
mode regulator. Then you might have some sort of useful KERS system
with bigger voltages / faster chargng. Although everything inside the
battery system would need redesigned for the higher voltages (Starter
solenoid, alternator, more batteries).

 

[James Sweet]

With current IC engines, they maybe getting more efficient but the
energy they create is still wasted alot. Heat goes out as mostly waste
, energy is used to drive various engine ancilaries (water pump, turbo,
steering) etc, and of course the old favourite ..tickover ,just keeping
it going.

In all fairness, a turbo is driven largely by otherwise wasted heat
energy in the form of exhaust pressure. There is some penalty due to the
increased exhaust restriction, but most of the energy it uses would
otherwise exit the tailpipe wasted. I don't know how much energy the
other accessories consume, but the alternator is one of the heaviest
loads, second only to perhaps the aircon compressor. Power steering is
really only significant at low speeds. Most of the friction losses are
within the engine itself, then the transmission and the rest of the
drivetrain.

 

[Jon Robertson]

Its a bit like some religious nutters they will believe anything except the
truth I eat them with alive .